Status Report

NASA Spacecraft and Expendable Vehicles Status Report 8 Apr 2004

By SpaceRef Editor
April 8, 2004
Filed under , ,

MISSION: Gravity Probe B (GP-B)


LAUNCH PAD: SLC-2, Vandenberg Air Force Base

LAUNCH DATE: April 19, 2004 NET

LAUNCH TIME: 1:01:20 p.m. EDT (10:01:20 a.m. PDT)

The launch of the Gravity Probe B spacecraft has been
postponed to no earlier than Monday, April 19. The additional time is
necessary to allow engineers to troubleshoot an apparent short in launch
pad ground support equipment. It is associated with a spacecraft
battery monitoring circuit. Without this circuit, the battery voltage
on the spacecraft cannot be remotely monitored from the pad during
certain essential operations. The launch time for Monday, April 19 is
10:01:20 PDT. Should the launch be postponed 24 hours for any reason,
the launch time is 9:57:24 a.m. PDT.

The spacecraft was moved from the payload processing facility to Space
Launch Complex 2 on Thursday, April 1 and mated to the Boeing Delta II
rocket. A spacecraft state-of-health check was successfully performed.
The next major test is the Flight Program Verification to be conducted
on Friday, April 9. This is an integrated test of the Delta II vehicle
and the Gravity Probe B spacecraft. The two-day operation to install
the two halves of the payload fairing around the spacecraft will follow
on April 12 and is the final major spacecraft associated activity to be
performed before launch.

Two days of major activities remain to be performed. On April 16, the
loading of the second stage with its complement of hypergolic
propellants is scheduled. On April 17, Flight Slews, which are launch
vehicle engine steering checks, will be performed. Also, the final Range
Safety beacon checks are scheduled.

Retraction of the mobile service tower, the gantry surrounding the Delta
II, is scheduled to occur at 11:30 p.m. on Sunday, April 18. Loading of
RP-1, a highly refined kerosene fuel, aboard the first stage, is
scheduled to begin at approximately 7:30 a.m. on Monday, April 19.
Loading of the cryogenic liquid oxygen into the first stage will begin
approximately an hour later.

The Gravity Probe B mission is a relativity experiment developed by
NASA’s Marshall Space Flight Center, Stanford University and Lockheed
Martin. The spacecraft will test two extraordinary predictions of
Albert Einstein’s general theory of relativity that he advanced in 1916:
the geodetic effect (how space and time are warped by the presence of
the Earth) and frame dragging (how Earth’s rotation drags space and time
around with it).

Gravity Probe B consists of four sophisticated gyroscopes that will
provide an almost perfect space-time reference system. The mission will
look in a precise manner for tiny changes in the spin axis direction.
Gravity Probe B will be launched into a 400-nautical-mile-high polar
orbit for a 16-month mission.

Government oversight of launch preparations and the countdown management
on launch day is the responsibility of the NASA Launch Services Program
based at John F. Kennedy Space Center. The launch service is provided
to NASA by Boeing Launch Services.




LAUNCH DATE: July 30, 2004 NET

LAUNCH WINDOW: 2:17:44 a.m. – 2:17:56 a.m. EDT

MESSENGER is at the Astrotech Space Operations facilities near
Kennedy Space Center where it is undergoing prelaunch testing. Testing
of the spacecraft’s radio system uplink and downlinks through the
KSC/JPL interface with the Deep Space Network (MIL-71) continues.
Autonomy testing is also continuing. This verifies MESSENGER’s ability
to operate on its own when not in direct contact with Earth.
Installation of thermal blankets continues.

On April 13, the spacecraft will be moved from its current
location in the hazardous processing facility, where it has been since
arrival, to an adjacent non-hazardous payload processing facility. The
remainder of its final assembly and testing will be completed there.
The spacecraft will return to the hazardous processing facility when
ready for fueling, spin balance testing and mating to the upper stage.

MESSENGER was built for NASA by the Johns Hopkins University
Applied Physics Laboratory in Laurel, Maryland.



LAUNCH PAD: SLC-2, Vandenberg Air Force Base

LAUNCH DATE: June 17, 2004

LAUNCH TIME: 6:01:53 a.m. – 9:04:53 a.m. EDT (3:01:53 – 3:04:53 a.m.

NASA’s Aura spacecraft, the latest in the Earth Observing
System (EOS) series, arrived at Vandenberg Air Force Base, Calif., on
April 1 to begin launch preparations. Packed in a special shipping
container, Aura was transported from Northrop Grumman Space Technology
(NGST) in Redondo Beach, Calif.

This week the Spacecraft Aliveness Test is under way. This
test verifies the spacecraft’s state of health after its trip from
Redondo Beach. Next week the Spacecraft Comprehensive Performance Test
will begin. This is a test of Aura’s instruments and onboard systems.

Aura’s four state-of-the-art instruments will study the
dynamics of chemistry occurring in the atmosphere. The spacecraft will
provide data to help scientists better understand the Earth ozone, air
quality and climate change.

The EOS Aura satellite, instruments and science investigations
are managed by NASA’s Goddard Space Flight Center in Greenbelt, Md.

SpaceRef staff editor.